Some pump drills I made

When I posted pictures of the brass indexing attachment I made for my rotary table,I mentioned that I spaced the holes with simple dividers,and drilled the holes with a pump drill. Some asked what is a pump drill.

They are a very old type of drill used mostly in clock making and silver smithing. They are only good for smallish holes,about 1/16" is the largest diameter that is practical. But,you can drill holes very exactly where you want them if you know how to use these simple drills.

The brass wheels are about 2 1/2" dia.. I am re posting the brass index for those who may not know what I referred to. After drilling the holes with the pump drill,I re drilled the holes with a small center drill to bevel the edges.

I made many bits for these type drills. Just made from drill rod and hammered flat,with 2 cutting edges filed on the ends of the drills. 1/8" shanks. The chucks hold only 1 size shank.

This is a batch I made,but I must have made a dozen others for craftsmen in Williamsburg to use.

This particular batch,I took with me when I went to the flea markets in Pennsylvania. I left them sticking up out of my back pack,no sign on them at all. Sold every one of them for enough to buy other stuff,and pay for the trip!

These are enjoyable to make because I can make all kinds of little decorative moldings on their drill rod shafts. The wheel for tightening the drills is knurled. Bad picture. It was 1" in dia.,and gave enough leverage to tighten the bits well. The split chuck has a tapered thread. I made the threads by backing up the cross slide as I cut them. They didn't have to be especially precision,but after you've done it a few times,nice tapered threads can be made.

Don't make the brass fly wheels too heavy. If you do,the drill runs slowly due to the inertia it takes to get them going.

Sometimes your Internet browser software will "Cache" a previous copy of that page on your computer rather than reload it every time, so that you are looking at an older version of a changing page. You can hit the "reload" button to get a fresh cop but sometimes the changes can take a while to percolate down.

Very nice drill's by the way, I know a guy who does a similar thing with tiny anvils and luthier planes he makes, sells quite a few wherever he goes.

I don't have a picture of just 1 drill,sorry. They are very simple. You hold the wooden cross bar in your fist with fingers wrapped around it,but not touching the vertical steel shaft. You give the brass flywheel a twist,which wraps the leather around the steel shaft. You then touch the steel shaft so it won't uncoil the leather,place the point of the drill on a punch mark,and push down on the wooden cross piece. The flywheel will start to spin,and will keep spinning and wrap the leather around the steel shaft as it goes past "neutral" and wraps the leather around the shaft in reverse,causing the wooden handle to rise up as the leather is wrapped. You push down,causing the flywheel to reverse direction and go "forward" so the drill will cut. You just continue to pump the wood handle up and down. The drill only drills on the forward stroke.

It is a quick and easy way to drill small holes in fairly thin metals or in wood. Useful in piercing work,sawing out inlay,where you need a hole to start a jeweler's saw blade in,etc..

The pump drills as shown are laying in what I called the neutral position: That is,the leather is not wrapped around the shaft.

It's like the old child's game when you took a large button,and whizzed it back and forth on a pair of strings between your hands.

The drill works from both the weight of the flywheel,but also the pressure of the hand pushing downwards on the cross bar. Glad you all are enjoying it. They sold these type drills until recently at jeweler's supply houses. Maybe someone still does.

If you have any kind of a lathe,they are fun to make. The moldings were made by freehand turning with small turning tools I make,and use on a rigged up tool rest.

You can make the flywheels run true by turning off most of the metal,and reaming an accurate(straight) center hole. Then,mount the flywheel on the un finished,un tapered shaft between centers,like a mandrel,and finishing it with light cuts. Then,take the flywheel off,and finish the steel shaft,leaving the area where the flywheel sits un touched. I suggest heating the flywheel before mounting to make its hole larger,then heating it again to get it off so you get a shrink fit.

To tell the truth,I cannot remember how I made these flywheels originally!! I'm just suggesting a method of being able to turn both sides of it,and getting it to run true.

I wonder if the same drill bits used in antique archimedes drills, which have the same forward-reverse motion would work better than a twist drill. They are shaped like a diamond point a bit like a spade drill and I think one edge cuts in one direction and the opposite edge cuts when spinning in reverse.

I did use diamond point flat bits that I made from 1/8" drill rod. It didn't take long to make such bits. I would go home and make several at lunch for the silver piercer. I had also made her a pump drill. It was how she managed to get started.

I wonder if the same drill bits used in antique archimedes drills, which have the same forward-reverse motion would work better than a twist drill. They are shaped like a diamond point a bit like a spade drill and I think one edge cuts in one direction and the opposite edge cuts when spinning in reverse.

The bits are more the shape of a straight flute router bit, only cut in one direction, clear the chips on the return stroke. Has been very handy over the years for drilling small precise holes in wood, such as a pattern of pilot holes for wood screws on cabinet hinges.

Never thought about metal drilling applications, I think I will roll my own set of bits for that purpose and give it a shot, thanks gwilson!

I did use diamond point flat bits that I made from 1/8" drill rod. It didn't take long to make such bits. I would go home and make several at lunch for the silver piercer. I had also made her a pump drill. It was how she managed to get started.

Ahh they are too, that's what I get for not really paying attention to the photo. I haven't seen any real close up photos of the bits themselves for archimedes type drills but they looked like a flattened rod with a diamond point larger than the shank and with no flutes. I guess the archimedes type's only advantage is you can control the pressure independent of the spinning and keep the downwards force when going both ways. What's the tip sharpening geometry like?. I'd like to make a flat bit drill for a friends collection and I wondered if the cutting edges of the point have relief or not. If it did, only one edge at a time would cut and the diamond flat on one side would be a bit smaller than the other side.

I just sharpened my bits to cut on the forward stroke. On the back stroke,the pressure is pretty much off the bit,because your hand is going up as the leather rewinds. Your hand is on the cross rod just enough to keep control of it.

There may be other ways to sharpen them,but I think they would be less efficient on the forward stroke.

Those straight flute bits that are found in the handles of some drills may not be hardened enough for drilling metal. They always filed pretty easily.

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